1、有提示框

NSMutableString * str=[[NSMutableString alloc] initWithFormat:@"tel:%@",@"123456"];

UIWebView * callWebview = [[UIWebView alloc] init];

[callWebview loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:str]]];

[self.view addSubview:callWebview];

2、直接撥打

NSMutableString *str=[[NSMutableString alloc] initWithFormat:@"tel:%@",@"123456"];

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:str]];